Download Lake Mulwala - Goulburn Murray Water

Lake Mulwala
Water Quality Study
Vegetation Assessment
The study recommended:
• Clearing in the Everglades area should be
strictly controlled;
• Riparian vegetation should be improved
around the entire lake but would be most
effective to focus on the Everglades and
Central Lake regions;
• Increasing the width of riparian vegetation
patches via a series of connected blocks.
This approach is preferable to increasing
the riparian width around the whole lake
(e.g. with a double row of trees); and
• Establishing an education program
highlighting the benefits of improving
vegetation cover in and around the lake,
and the effects of undesirable species.
As owner and manager of most of the
foreshore land on the Victorian side of the
lake, Goulburn-Murray Water on behalf of
the Murray-Darling Basin Commission is
committed to protecting and improving native
vegetation to enhance water quality and the
ecological health of Lake Mulwala.
This brochure is part of a series, which also
includes more detailed information on Lake
Mulwala’s water quality and how you can contribute
to a healthier lake. To obtain other brochures from
the series contact:
Goulburn–Murray Water Yarrawonga Weir
03 5744 3137
Moira Shire Council
03 5871 9222
Corowa Shire Council
02 6033 8999
Or visit www.g-mwater.com.au.
To view the Murray-Darling Basin Freshwater
Research Centre Water Quality report visit
www.g-mwater.com.au.
The spread of invasive Crack Willow trees is a
potential threats to the health of the lake.
Vegetation Assessment
Native vegetation in and around Lake
Mulwala was the focus of a study
undertaken by the Murray-Darling
Freshwater Research Centre in
2004-2005.
The study was part of a broader Water
Quality Study on Lake Mulwala which
reviewed existing literature on the health
of the lake, assessed current conditions
and made recommendations for future
monitoring.
The study found, apart from the
Everglades region, vegetation around
most of the lake consists of a narrow
strip. This strip, known as the riparian
zone, is stressed and in poor condition,
due to human-induced activity in
surrounding areas. The zone consists
mostly of mature River Red Gums
(Eucalyptus camaldulensis) and at the
western end, exotic tree species such as
Weeping Willow (Salix babylonica).
The study found:
• About 400 ha of land at Lake Mulwala is
vegetated, although more than a third of
the lake’s edge is not vegetated;
Healthy native vegetation is an essential
component for healthy waterways.
At Lake Mulwala it provides important
ecosystem functions such as:
• At least 33 different aquatic and riparian
species were observed;
• Filtering runoff of sediments, nutrients
and other pollutants to the lake;
• Habitat for native bird, animal and fish
species; and
Main Basin
Central Region
• Riparian vegetation is relatively healthy in
the Everglades region but ecological value
declines from east to west;
Everglades
• Stabilising the lake bed and banks to
prevent erosion.
Improved ecological health of Lake
Mulwala is a key objective of the
Lake Mulwala Land and On-Water
Management Plan. The study provided
a detailed baseline of information
on the current state of vegetation.
This will be used to enable better
management and the development
of an ongoing monitoring program.
This brochure is part two of a series
outlining information on the vegetation
assessment component of the study.
For the purpose of the study, the lake was
divided into three main regions including the
Main Basin at the western end of the lake, the
Central Lake Region and the Upper Eastern
Lake region known as the ‘Everglades’ where
the River Murray meets the Lower Ovens River.
A Geographic Information System was used
combined with on-ground assessment and
sampling techniques to assess the health
of the riparian and aquatic vegetation.
Assessments confirmed the Everglades
region exhibits vegetation of high ecological
value that requires careful management and
protection. The high diversity (30 species
recorded) and abundance, good condition and
ongoing regeneration of in-channel vegetation
provides healthy habitat for native animals.
• In the Central Lake region, riparian
vegetation mostly consists of a single row
of trees. Although Kyffins Reserve takes
in a large area of vegetation, including
three ha of in-channel vegetation.
• In the western Main Basin region, only one
third of the lake’s edge is vegetated, almost
entirely with exotic species (99%) which
are mostly Weeping Willows. In-channel
vegetation is scarce with no aquatic
species recorded.
• While 95% of the vegetated lake area
is comprised of native species, this is
predominantly remnant mature River Red
Gum (Eucalyptus camaldulensis), with little
evidence of regeneration.
• The spread of invasive Crack Willow trees,
Dense Waterweed and Arrowhead are
potential threats to the lake’s health. These
species out-compete native vegetation and
provide limited habitat for native species.
Only one extensive vegetation survey had
been carried out prior to the 2004-2005
study, making it impossible to predict
long-term trends.
However, using the baseline data gathered
in this study, a comprehensive standardised
monitoring program for vegetation at Lake
Mulwala has been developed. The monitoring
program will be repeated every five years,
and will assess changes in abundance,
composition, distribution and condition of
riparian and aquatic vegetation.